/*
 * Copyright 2012 The Netty Project
 *
 * The Netty Project licenses this file to you under the Apache License,
 * version 2.0 (the "License"); you may not use this file except in compliance
 * with the License. You may obtain a copy of the License at:
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations
 * under the License.
 */
package org.jboss.netty.example.discard;

import java.util.logging.Level;
import java.util.logging.Logger;

import org.jboss.netty.buffer.ChannelBuffer;
import org.jboss.netty.buffer.ChannelBuffers;
import org.jboss.netty.channel.Channel;
import org.jboss.netty.channel.ChannelEvent;
import org.jboss.netty.channel.ChannelHandlerContext;
import org.jboss.netty.channel.ChannelState;
import org.jboss.netty.channel.ChannelStateEvent;
import org.jboss.netty.channel.ExceptionEvent;
import org.jboss.netty.channel.MessageEvent;
import org.jboss.netty.channel.SimpleChannelUpstreamHandler;
import org.jboss.netty.channel.WriteCompletionEvent;

/**
 * Handles a client-side channel.
 */
public class DiscardClientHandler extends SimpleChannelUpstreamHandler {

	private static final Logger logger = Logger
			.getLogger(DiscardClientHandler.class.getName());

	private long transferredBytes;
	private final byte[] content;

	public DiscardClientHandler(int messageSize) {
		if (messageSize <= 0) {
			throw new IllegalArgumentException("messageSize: " + messageSize);
		}
		content = new byte[messageSize];
	}

	public long getTransferredBytes() {
		return transferredBytes;
	}

	@Override
	public void handleUpstream(ChannelHandlerContext ctx, ChannelEvent e)
			throws Exception {
		if (e instanceof ChannelStateEvent) {
			if (((ChannelStateEvent) e).getState() != ChannelState.INTEREST_OPS) {
				logger.info(e.toString());
			}
		}

		// Let SimpleChannelHandler call actual event handler methods below.
		super.handleUpstream(ctx, e);
	}

	@Override
	public void channelConnected(ChannelHandlerContext ctx, ChannelStateEvent e) {
		// Send the initial messages.
		generateTraffic(e);
	}

	@Override
	public void channelInterestChanged(ChannelHandlerContext ctx,
			ChannelStateEvent e) {
		// Keep sending messages whenever the current socket buffer has room.
		generateTraffic(e);
	}

	@Override
	public void messageReceived(ChannelHandlerContext ctx, MessageEvent e) {
		// Server is supposed to send nothing. Therefore, do nothing.
	}

	@Override
	public void writeComplete(ChannelHandlerContext ctx, WriteCompletionEvent e) {
		transferredBytes += e.getWrittenAmount();
	}
	
	@Override
	public void exceptionCaught(ChannelHandlerContext ctx, ExceptionEvent e) {
		// Close the connection when an exception is raised.
		logger.log(Level.WARNING, "Unexpected exception from downstream.",
				e.getCause());
		e.getChannel().close();
	}

	private void generateTraffic(ChannelStateEvent e) {
		// Keep generating traffic until the channel is unwritable.
		// A channel becomes unwritable when its internal buffer is full.
		// If you keep writing messages ignoring this property,
		// you will end up with an OutOfMemoryError.
		Channel channel = e.getChannel();
		while (channel.isWritable()) {
			ChannelBuffer m = nextMessage();
			if (m == null) {
				break;
			}
			channel.write(m);
		}
	}

	private ChannelBuffer nextMessage() {
		return ChannelBuffers.wrappedBuffer(content);
	}
}